hello EMC group,
we are currently evaluating the move from stainless steel to zincor for some parts of the medical equipment that we manufacture. Some parts have a shielding function. The equipment is used in an air-conditioned environment. Of course there is storage and transportation to consider. We are not blindly moving to zincor and we plan to test the effects of moisture-humidity on the zincor. In the past we have performed cyclic and static damp-heat tests on the stainless stell versions of our equipment, but the testing revealed very little information and we abondemned damp-heat testing. The plan is to evaluate EMC performance of zincor equipment before and after a static damp-heat test of 40 degrees at 85% or 93% RH for about 1 or two weeks. Such a test is described in IEC 600068-2-78. The product is not packaged, power off and ready for use. The scope of this standard is transportation, storage and operation under high humidity. Bruce Archambealt (IBM) describes in "Effect of corrosion on the electrical properties of conducted finishes" 1989 Int Symph on EMC, a test to simulate 5-8 years of exposure in a commercial computer environment. The environmental parameters are humidity, temp, nitrid oxide, chlorine and hydrogin sulfide (duration 14 days). We only control the temperature and humidity. One last note: the equipment is class A and the shielding is of secondary importance. We control EMI by means of frequency management and spread-spectrum techniques. Some known EMI sources are not even in the shielded electronic box". The equipment is rather open because of its function. Wrt immunity I would assume that ESD would bridge corrosion easily. I have some questions: -1- who has similar experiences? -2- how important is it to control nitrid oxide, chlorine and hydrogin sulfide levels? -3- are there safety issues??? For example leackage currents, protective earth bonding, ...?? (I am not an safety specialist, but rather EMC & signal integrity) -4- possible effects on ESD, radited immunity (level 10V/m)??? -5- any suggestions for temperature, humidity and test duration and how this translates into "exposure time". Thank you, Jan Vercammen - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
